Interface circuit for processor controlled system and vehicle laundry system utilizing such interface circuit

ABSTRACT

A smart module circuit board carries a programmable microprocessor and a plurality of relay type interface circuits for use in organizing relatively high voltage input devices and output devices into a complex system wherein a programmed combination of input device signals determines when and if to energize one or more output devices in the system. The interface circuit comprises input and output stages which operate on logic level voltages and which are decoupled by opto-couplers from a relatively high voltage energization circuit which passes through a relatively high voltage electrical device. The energization circuit comprises a triac which is operated by the output stage in response to outputs from the microprocessor, a manual switch connected in parallel with the triac so that a given electrical load device can be manually activated and a multi-colored LED for indicating the conditions of the input and output circuits individually and in combination. The smart modules are utilized in a vehicle laundry having a master computer for overall control of multiple smart modules, the microprocessor of each smart module being independently operable to control at least a portion of the laundry system in the event of a failure of the master computer.

FIELD OF THE INVENTION

This invention is in the field of circuits through which it is possibleto electrically isolate, monitor and control electrical devices such asswitches and motors. The invention pertains more particularly to a highflexibility interface circuit for (a) providing inputs from a firstclass of electrical devices to a controller and (b) applying outputcommands from the controller to a second class of electrical devices forthe purpose of regulating the actions and functions of such devices in acomplex system.

BACKGROUND OF THE INVENTION

There are many industrial uses of complex systems in which multiple anddiverse electrical devices are electrically isolated, monitored and/orcontrolled by way of relay or relay-like circuits which may operateunder the management control of a computer controller. By "controller"we refer to a management device such as a programmable digital processorwhich receives inputs in the form of electrical signals representing atleast in part the conditions of a first class of real world electricaldevices and which uses those inputs to create commands or outputs in theform of electrical signals which are applied directly or indirectly to asecond class of real world electrical devices to determine thefunctional status thereof. The processor further relates or coordinatesinputs to outputs according to a program defining the overall functionsor function to be achieved by such devices in a complex system. By "realworld" we refer to such devices as switches, solenoids and motors whichare associated with work production and/or physical movement or othercondition changes in an industrial system as opposed to merecalculations which might occur wholly within a data processor using onlylogic level signals. The controller may, as stated above, comprise atits heart a general purpose digital microprocessor chip capable ofperforming data processing and/or management tasks of many kinds.Alternatively, it may comprise a special purpose computer or even a hardwired circuit, the "program" portion of which is found in the form ofhardware or firmware rather than the more traditional applications andoperating system software. In general, however, complex systems inindustrial applications of all kinds more and more typically includemicroprocessor chips which are not only flexible in operation andapplication, but are widely and inexpensively available from varioussources and manufacturers such as Intel but are also widely andgenerally understood and used by engineers and technicians throughoutthe United States and the world.

An example of an industrial application comprising input type real worlddevices and output type real world devices operating in a complex systemunder the control of a data processor is a vehicle laundry wherein suchoperations as vehicle proximity detection, vehicle length and sizeassessment, soap spraying, water spraying, brushing, forced air drying,wheel washing and polishing are performed in spaced and overlappingsequences. In such a system, devices which provide condition orfunction-signaling inputs to a controller-programmer may include, by wayof example and not by limitation, vehicle proximity detectors such aslimit switches, wand switches and electric eyes, conveyor drive shaftangle encoders, emergency stop switches, keypads, coin boxes and avariety of other devices having contacts which create open and closedcircuit conditions. Output or function-causing devices the excitationand operation of which are subject to a remote external controlaccording to the management program found in a controller may include,by way of example and not by limitation, scrubbing brushes, airturbines, hydraulic and pneumatic cylinders, solenoids, pumps, lights,doors, wheel washers, motors and motor starting circuits.

In a more complex but nevertheless typical vehicle laundry it may bedesirable to provide a variety of proffered service packages rangingfrom a simple wet wash to drying, waxing, the application ofanti-corrosion agents and wheel washing. The customer may directlyselect such combinations by way of a credit card reader and keypad ormay indirectly make such selections through an attendant who enters anappropriate code from a remote station and provides the customer with acoin or token or code input to simply initiate the operation of thesystem.

In addition various complex functions are or may be provided in avehicle laundry such as vehicle proximity detection and vehicle sizeassessment thereby to schedule the energization and deenergization ofvarious output devices in the system for the purpose of minimizingelectrical energy consumption and cost.

In addition it is highly desirable to utilize a general purpose computeras part of the controller of a complex system in order that the generalpurpose digital computer be available for use in peripheral but relatedapplications such as financial record keeping, maintenance recordkeeping and scheduling, payroll, employee attendance, machinery usagelevels and other data collection and/or coordination functions which aretypically associated with the conduct of a retail merchandizingoperation. The general purpose computer may, however, be placed at thetop of a hierarchy which includes lower order computers which arecapable of independent action in the event the master computerexperiences a failure or is temporarily unavailable.

Many other industrial applications of a complex nature involving inputtype electrical devices and output type electrical devices theenergization and performance of which are to be coordinated by means ofa controller will be apparent to those skilled in the art. Again by wayof example and not by limitation, examples of such systems includebaggage handling, conveyor systems, automated assembly systems, medicalanalysis and evaluation systems, access and security systems,construction machinery and other applications characterized by multipleoperations on a common workpiece in sequential and coordinated fashion.

One of the problems associated with the construction and operation ofcomplex systems operating under management of a computer-type controlleris the typical need to customize electrical circuitry, particularly theinterface circuitry which ties the real world electrical devices to thecontroller either as input devices or output devices. The devicesthemselves may vary as between simple input devices such as switches,and more complex and power-consuming output devices. In addition, thedevices within a single class may vary widely as to excitation voltageand power consumption; e.g., a simple 100 watt filament type light bulbpresents an entirely different electrical energization interfacingrequirement than an induction motor that might be used to drive a highvolume, high velocity air turbine.

Another problem confronting the control circuit designer is thedesirability of providing not only for coordinated or integratedautomatic control of the various controlled or output devices in a givensystem but also of providing for independent manual operation ofselected devices and, moreover, of providing for overall operation in acoordinated fashion even though the master computer associated with thesystem may be down as a result of a malfunction or failure. It isdoubtless a fact of life that many a complex and elegant computercontrolled system has been rendered unproductive by reason of thefailure of an inexpensive integrated circuit in a device upon which theoverall system is dependent.

SUMMARY OF THE INVENTION

It is an object of this invention to provide an interface circuit havingrelay-like characteristics which is generally applicable to the task ofinterfacing various types of electrical devices having conductive andnonconductive conditions with a management device of the type describedabove; i.e., a controller of the type which is programmable tocoordinate the functions of various real world electrical devicesthrough the production of output commands and which is further capableof receiving inputs in the form of electrical data signals from otherreal world electrical devices and which exhibits flexibility inapplication and operation and in the accommodation of a wide variety ofelectrical devices of both input and output character.

It is a further object of this invention to provide an interface circuitof the character described above which provides not only for theprogrammed or automatic control of a wide variety of output typedevices, but which also provides for the selective manual energizationand operation of individual devices and which, at the same time,provides a logical input to the controller to show that a manual deviceoperation or selection has occurred.

It is a further object of the invention to provide a relay-typeinterface circuit capable of controlling the application of power to aload device wherein the operating state of the interface circuit and thecondition of the associated load device is visually displayed in aneasily recognized and non-ambiguous fashion.

It is a further object of the invention to provide an interface circuitof the type and character described above which is utilizable inmultiples and on circuit boards in a complex industrial system or devicesuch as a vehicle laundry having multiple input type devices providingdata signals as well as multiple output devices which receive commandsfor programmed operation.

It is a further object of the present invention to provide an interfacecircuit of the type and character described above in a complexindustrial system of the type described above wherein the systemoperation is conducted under the control of a system having both masterand local controller hierarchy such that a loss or failure of the mastercontroller does not render the overall system inoperable but, rather,wherein full programmed and coordinated operation of the system ismaintained by virtue of a microprocessors which are locally stationed oncircuit boards preferably carrying multiple interface circuits.

It is a further object of the present invention to provide a controllerfor a complex industrial system consisting of input devices such asswitches and output devices such as motors and lights wherein the outputdevices are called into service in accordance with conditions signalledby the input devices and coordinated by an overall function program. Anexample given by way of illustration is a vehicle laundry whereinvehicles travel through stations arranged along a conveyor line and areoperated upon according to a pre-defined program. Input devices such aslimit switches, and electric eyes and conveyor shaft angle encoderssignal the presence of a vehicle at each of the stations as well as theoperative condition of the devices associated with each station. If alogically-coordinated set of conditions is satisfied; as evidenced byappropriate input signals to the controller; e.g., (a) vehicle present,(b) function-performing device operative, (c) function selected, and (d)no emergency stop signal present, the controller creates an output to afunction-causing device turning that device on at and for a prescribedtime.

The controller is preferably arranged on a circuit board with multipleinput/output device interfaces and equipped with sufficient local memoryto carry out the programming needs of a number of output devices as wellas at least the input devices associated with those output devices;e.g., a soap dispenser pump and the liquid level detector in the soapreservoir. The combination of the controller and the multiple interfacesis termed a "smart module."

Preferably, each interface circuit is equipped with a remote switch toturn a device on and off under the control of the controller, and amanual switch by which the device may be turned on and off independentof a function-coordinating program. Moreover, each interface circuit ispreferably, but not necessarily, equipped with a visual indicator todisplay its operating status; e.g., AUTO, MANUAL and OFF.

These and other objects and advantages of the invention will be bestunderstood from the reading and understanding of the followingspecification in which the design and operation of an illustrativeinterface circuit is given in combination with the disclosure of avehicle laundry system utilizing multiple interface circuits of the typeand character described in detail herein.

Specifically, in the interface circuit illustratively described hereinis of the type suitable for use in a combination with variouscontrollers including microprocessor type controller which can producecommand signals or outputs for controlling through the interface circuitthe condition of a first class of electrical devices and which iscapable of receiving via the interface circuit signals in electricalform supplied thereto in accordance with the operating condition ofanother second class of electrical devices. The interface circuitpreferably comprises:

A) a relatively high voltage electrical device energization circuithaving a first switch therein for opening and closing the circuit,usually in response to a command signal produced by a controller;

B) a relatively low voltage circuit adapted to receive commands from acontroller and an output coupled to the first switch means to place thefirst switch means in an open circuit condition or a closed circuitcondition according to the content of the input command;

C) a second switch means, possibly intended for manual operation, in theelectrical device energization circuit also for opening and closing thecircuit independently of the first switch means;

D) means interconnecting the second switch means to the input of thecommand circuit for providing a command equivalent signal thereto whenthe second switch means is in the closed circuit condition thereby toenable the circuit as if a command had been produced;

E) sensing means, illustratively in the form of a high resistivity shuntcircuit connected to an opto-coupler, coupled to the energizationcircuit and having a first output signal condition when the circuit isclosed and a second different output signal condition when the circuitis opened; and

F) a relatively low voltage controller input circuit means coupled tothe sensing means to produce an input to the controller according to thesignal condition of the sensing means.

In the preferred form hereinafter illustrated, the interface circuit ispackaged similar to a relay so as to be mountable along with multipleidentical interface circuits on a common printed circuit board,hereinafter called a "smart module," having a local microprocessor whichitself is fully operative and fully programmed to carry on the needs andfunctions of a system, or a substantial portion of the system. Theoverall function of the local microprocessors may be under the controlof a larger and/or remote general purpose master processor which mayperform other tasks as well as the management of the complex systemdescribed herein. So packaged, it is desirable and preferred to providein connection with each interface circuit an indicator, preferably inthe form of a multi-color LED, for producing a coordinated displayrepresenting the states of the command circuit, the controller inputcircuit and the manual switch. Purely by way of example and not by wayof limitation, the LED may be connected to the output circuit to providea GREEN indication when an input circuit portion of the interfacecircuit is active, an RED output condition when the output circuit isunder the control of the controller and active and an AMBER conditionwhen the manual mode of operation is selected via the manual switch. Afourth condition may be equated to the absence of any color at all fromthe LED. Of course, multiple single-color LED's may also be used as wells other types of visual indicators.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an illustrative interface circuit;

FIG. 1A is a duplicate of FIG. 1 with enhanced representations of thoseportions of the circuit which are active when the circuit is undercontroller control, the load circuit is intact and a command output ispresent;

FIG. 1B is a duplicate of FIG. 1 with enhanced indications to show thoseportions of the circuit that are active when the circuit is under thecontrol of the controller and an electrical load device controlledthereby is defective and open circuited;

FIG. 1C is a duplicate of FIG. 1 with enhanced representations of thoseportions of the circuit which are active when the circuit is under thecontrol of the controller, no command signal is generated and the loaddevice is unenergized but operative; i.e., no open circuits or faults;

FIG. 1D is a duplicate of FIG. 1 with enhanced representations of thoseportions of the circuit which are active when a manual operation of anoutput device is selected and the device is operable; i.e., no opencircuits or faults are present;

FIG. 1E is a duplicate of FIG. 1 with enhanced representations of thoseportions of the circuit which are active when used solely in connectionwith an input device which is closed circuited and, therefore, sendingan input signal to the microprocessor;

FIG. 2 is a block diagram of a vehicle laundry utilizing multipleinterface circuits of the type disclosed in FIG. 1 on a common circuitboard for controlling the functions of various electrical devices in acomputer controlled, multi-function vehicle laundry; and

FIG. 3 is a table of logic conditions in the input and output portionsof the FIG. 1 circuit as related to operating condition.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT

Referring to FIG. 1 there is shown a circuit 22 for use both as inputand output interface between real world electrical devices and acontroller in the form of a general purpose digital microprocessor 8 ofthe type which is capable of producing output commands on digital outputbus 10 and receiving data inputs in digital form on digital binary inputbus 12. Although shown in FIG. 1 as single lines, busses 10 and 12normally comprise multiple parallel lines and accommodate multipledevices by way of a multi-bit code. The microprocessor 8 may be andpreferably is equipped with an input port 14 by which the microprocessormay receive data from other processors or from input accessories such asa keypad or keyboard. Microprocessor 8 is further provided with a memory16 for program storage and retrieval.

The circuit 22 as shown in FIG. 1 is connected to an electrical loaddevice schematically represented at 20 which is connected acrossterminals 4 and 5 of a terminal block 24. The load device 20 is of atype which is capable of doing work and is subject to automatic orprogrammed coordinated energization by the microprocessor 8 by way ofoutput command line 10 and also by manual operation through adouble-pole, double-throw switch 32 as hereinafter described. Circuit 22comprises six distinct sections: a load device energization circuitsection 26 connected between terminals 1 and 4, an output circuitsection 36, a sense circuit section 62, an input circuit section 71, adisplay or indicator 86 and a manual mode select circuit section 80.Details of all six circuit sections are hereinafter described.

The load energization circuit 26 comprises a fuse 28 and a firstremotely controllable switch means in the form of a triac 30 which iscapable of conducting AC line voltages over a wide range of voltagevalues and which is capable of being switched between conductive andnon-conductive states by means of remote signals applied to a gatecircuit through an opto-coupler 44 which couples the load energizationcircuit 26 with the output circuit 36 as hereinafter described. Theenergization circuit further passes through the switch 32 and aninductor 33 en route to terminal No. 4 in the terminal block 24.

The output circuit 36 comprises a differential amplifier 38 whichproduces a high output whenever it receives a command frommicroprocessor 8. To achieve this, the positive input of amplifier 38 isconnected by way of line 60 to the microprocessor output 10 and to themanual mode select circuit 80. The negative input is connected to thejunction between bias resistors 50 and 52. The high side of resistor 52is connected to the input circuit 71 via resistor 53 and via line 54 tothe switch 32.

The output of the differential amplifier 38 is connected by way ofresistor 55 and line 40 to the LED component 42 of the opto-coupler 44to close; i.e., render conductive, the AC switch portion 46 of theopto-coupler which interconnects the bias resistor 48 to the gateelectrode of the triac 30 in the load energization circuit 26.Differential amplifier 38, therefore, has the capability of controllingthe state of conductivity of the triac 30 in the load energizationcircuit 26. When there is no output command on line 10, the differentialamplifier 38 produces a logical low output and the opto-coupler 44 isnon-conductive. Therefore the triac 30 is also nonconductive. When theoutput on line 10 goes high, the differential amplifier conductsactivating opto-coupler 44 and the triac 30 also conducts.

The sense circuit 62 connected between terminals 1 and 4 of the terminalblock 24 comprises opposite polarity diodes 64 and 66, capacitor 67 andthe LED stage 68 of an opto-coupler 70 which couples the sense circuit62 to the input circuit 71. The sense circuit 62 is of much higherimpedance than that of the energization circuit 26 and conducts a smallamperage current only when the load 20 is intact; i.e., no open circuitor fault, but neither the triac 30 nor the manual switch 32 is closed toestablish current flow in the energization circuit 26. When the triac 30is conductive, essentially no current flows through the sense circuit 62because of the much lower impedance of the conducting triac 30 which isin parallel with the sense circuit 62. A no-current condition alsoexists in the sense 62 circuit 30 whenever the triac 30 isnon-conducting but the load is open-circuited due to an internal faultand is, therefore, in a non-operable condition. As used herein, "state"refers to the ON or OFF state and "condition" refers to operable orinoperable. The impedance of the sense circuit 62 to the line voltage issuf ficiently high that the power applied to the load device 20 throughthe sense circuit 62 is insufficient to cause effective operationthereof; i.e. , if the load device is a motor, the sense circuitcurrent, even though enough to excite the sense circuit 62, is notenough to set the motor into motion to do work.

The display device 86 is a three-color LED capable of generating RED,GREEN and AMBER visual outputs. A fourth output state is represented bythe OFF condition.

The terminal block 24 connections are as follows:

    ______________________________________    Terminal            Application    ______________________________________    1, 2                line voltage    3                   ground    4, 5                load    ______________________________________

The line voltage may be anything within the capabilities of the triac 30and is completely isolated from the low voltage circuit components bythe opto-couplers. In a practical embodiment voltages from 24 to 220v ACare used. The triac 30 may, of course, be replaced with other types ofremotely controllable electronic switches.

The input circuit 71 comprises a second differential amplifier 74 whichproduces a high output whenever the opto-coupler 70 conducts; i.e,whenever there is current in the sense circuit 62 showing that the loadis intact but neither switch 30 nor 32 is closed. To accomplish this,the positive input of amplifier 74 is connected to a junction betweenbias resistors 75 and 77 and also through a diode 82 to manual selectline 81 for purposes hereinafter described. The negative input of thedifferential amplifier 74 is connected to the high side of capacitor 75and to the output stage 72 of the opto-coupler 70. When the opto-coupler70 is non-conductive, the negative input is high and the amplifieroutput is low. The output of the differential amplifier 24 is connectedvia line 81 to the data signal input 12 of the microprocessor 8. A diode79 is connected between the positive input and the output of amplifier74 for purposes to be described.

In general, when the opto-coupler 70 conducts, the negative input goeslow and the output of the differential amplifier 74 goes high to providea data signal input to the microprocessor 8. This occurs whenever theload 20 is operable; i.e., no faults or open circuits, but neither ofthe two parallel switches 30 and 32 is closed to actually energize theload 20.

Finally the circuit 22 comprises a manual mode select circuit 80consisting primarily of the double-pole, double-throw switch 32, line 34which connects a portion of switch 32 in parallel with triac 30, anddiodes 82 and 84 connecting line 81 to the positive inputs of thedifferential amplifiers 74 and 38, respectively. The three-color LEDindicator 86 provides a visual indication of the condition of theenergization circuit 26 and the operable state of the load device 20.Indicator 86 comprises an upper GREEN light stage 88 connected to theoutput of the differential amplifier 74 and a lower RED light stage 90connected to the output of the differential amplifier 38. In general,whenever only amplifier 74 produces a high output, the LED 88 indicatorshows GREEN; whenever only the amplifier 38 produces a high output, theLED 90 shows RED; whenever both LEDs 88 and 90 are active, the indicator86 shows AMBER. Obviously, when neither of the LED 88 and 90 is active,the indicator 86 is unilluminated or OFF.

Switch 32 has three positions: MANUAL, AUTO and OFF. The OFF positioncan be anywhere between MANUAL and AUTO. When in the AUTO position, theload energization circuit 28 passes through the triac 30. In thisposition, a DC source VCC connected to terminal 56 is then connected byline 54 to each of the differential amplifiers 38 and 74. The amplifiers38 and 74 have high input to the negative input and low output. When inthe MANUAL position, the DC bias source VCC is connected by way of line80 and diodes 82 and 84 to the input and output circuits respectively tocreate two HIGH outputs. In fact, only amplifier 38 goes HIGH; the HIGHoutput from amplifier 74 being simulated by the diode 72 which actuallyapplies VCC to the GREEN LED stage 88. This activates both stages of theLED indication 86 to show an AMBER visual indication. When in the MANUALposition, the left side of the double-pole, double-throw switch 32completes the load energization circuit 26 between terminals 1 and 4whether or not the triac 30 is conductive.

Capacitor 58 provides a dissipation path for short term voltagetransients such as from lightning strikes;, circuit 96 is for signalvoltage conditions; and diodes 97 provide noise filtration. Circuitcomponent values for an exemplary circuit are given in Table 1.

Operation AUTO Mode, Microprocessor On

Referring to FIG. 1A the circuit 22 is shown in the condition when themicroprocessor 8 is producing a command signal on line 10 and the doublepull double throw switch 32 is in the right hand position; i.e., theAUTO position. Under these circumstances, the load energization circuit26 is established through the triac 30 and, because differentialamplifier 38 is receiving a command signal on line 10 the output of theamplifier 38 is high. This high output is applied by way of line 40 tothe LED side of the opto-coupler 44 to activate the gate electrode andrender triac 30 conductive. The high output of amplifier 38 is alsoapplied to the lower stage 90 of the indicator LED 86 to produce a REDvisual indication which is equated with the active or energizedcondition of load 20 in the AUTO mode.

Because a low impedance, high power-level energization circuit 26through the triac 30 is conductive, there is insufficient currentthrough the high impedance, lower power-level sense circuit 62 toactivate the opto-coupler 70 and the output of differential amplifier 74is low; there is neither a data signal input to the microprocessor 8 noractivation of the upper or GREEN stage 88 of the LED indicator 86. Inshort when, the microprocessor 8 commands energization of the loaddevice 20, high power-level energization is completed through triac 30and the logical combination of input and output to the microprocessor 8is as shown in FIG. 3. The term "high power-level energization" meansthat the load device receives sufficient power from the line source todo work.

Operation AUTO Mode On, Load Open Circuited

Referring now to FIG. 1B, the active portions of the circuit 22 areillustrated in enhanced fashion under those conditions which obtainwhenever the switch 32 is in the AUTO position, the microprocessor 8 iscommanding an output or energization of the load 20 but the load,because of an internal fault or open circuit, does not conduct.

Under these conditions, the differential amplifier 38 produces a lowoutput so the RED side of the energization circuit 26 is non-conducting.The live voltage is applied only to the sense circuit 62. However, thedefective load 20 permits no current to flow through the sense circuit62 and the inputs to the amplifier 74 produce a low output. The GREENside 88 of the LED indicator 86 is also unilluminated. The OFF conditionof indicator 86 represents a failure in the load device 20.

AUTO Mode On, Microprocessor Off

Referring to FIG. 1C, those portions of the circuit which are activewhen the switch 32 is in the AUTO mode but the microprocessor 8 isproducing no output command are shown in enhanced fashion. As shown inFIG. 1C, the load 20 is intact; i.e, there are no internal open circuitsor faults.

Because there is no command signal on line 10, the output ofdifferential amplifier 38 is low and triac 30 is non-conductive. Thereis, however, a high resistivity circuit completed from the source ofpotential associated with the load 20 through the diodes 64 and 66 ofthe high resistivity sense circuit 62 in sufficient quantity to activatethe LED stage 68 of the opto-coupler 70. This applies a low signal tothe negative input of amplifier 74 and turns the differential amplifieroutput high. The high output condition of the differential amplifier 74turns the GREEN LED section of the visual indicator 86 on as shown inthe contents of Table 2. The GREEN condition is consistent with theselection of the AUTO mode, and an intact load in the absence of acommand. In other words, the load is intact but in the standby orunenergized condition of the AUTO mode.

MANUAL Mode Load Intact

Referring now to FIG. 1D circuit 22 is shown in the condition whichoccurs whenever the switch 32 is moved to the MANUAL position and theload is intact.

The right side of the double-pole, double-throw switch 32 connects theDC source VCC to the positive inputs of each of the differentialamplifiers 38 and 74. Amplifier 38 goes high to activate the lower orRED portion of the LED indicator 86. The high voltage signal throughdiode 84 is conducted around amplifier 74 through diode 82 to the inputline 12 to the microprocessor 8 and to the upper or GREEN section 88 ofthe LED indicator 86. Because both RED and GREEN annunciators 90 and 88are on, the composite output color is AMBER. The energization circuit 26is completed through the switch 32 but not through the triac 30 eventhough the gate electrode receives a high signal. The fact that one ofthe two parallel switches 30, 32 is closed prevents any significantcurrent flow through the sense circuit 62 and the opto-coupler 70remains off. The opto-coupler 44 is active but the triac switch 30cannot conduct because of the open circuit at switch 32.

From the foregoing it is apparent that the AMBER display from the visualindicator 86 is associated with the selection of the manual mode nomatter what the condition of the load 20. It is possible for theoperator of the system to determine by visual inspection of the circuit22 in physical form that the switch 32 is in the manual position andthat manual operation of a load device is underway. It is a simplemanner to logically identify those lines in the program 16 associatedwith the microprocessor 8 with a particular load device and loadcircuit. Therefore, a record can be readily made in the microprocessor 8and stored as data for incorporation into a log or report to be made atregular intervals or on demand to advise management that a load devicehad been activated at a particular time. As hereinafter described thiscan be associated with a clock signal so that the time of day and theduration of the manual selection of the particular load device can beidentified.

Input Condition

Referring now to FIG. 1E the circuit 22 is shown with enhanced portionsto illustrate those elements which are active when the associated deviceis in the "input" class; i.e., is connected between terminals 1 and 2and is merely a condition-signaling device rather than a motor orsolenoid device which does work. The function of circuit 22 isessentially to produce a high signal condition on line 12 when the load20' is a closed circuit and a low signal condition when the load 20' isan open circuit.

To utilize the circuit 22 in the input mode it is necessary to connect a"dummy" load 20D across the terminals 4 and 5. The dummy load 20Dpreferably assumes the form of a small capacitor to provide a currentpath through the circuit 26. The actual input device 20' is connectedacross terminals 1 and 2 such that when the terminals or contacts of thedevice 20 close, a circuit is formed between the source of potential andthe sense circuit 62 to activate the LED stage of the opto-coupler 70and provide a signal to the negative input of the differential amplifier74. When the negative input goes low, the output goes high and a datasignal on line 12 to the microprocessor 8 is created.

As stated above, all of the individual input lines 12 are logicallyidentified by the program portion 16 of the microprocessor 8 with aparticular device or location in an industrial system such that eachinput line has its own "device identity" in the overall coordinationprogram. The high output from differential amplifier 74 also activatesthe GREEN stage 88 of the LED indicator 86 advising the operator that aninput device is in the closed circuit or active condition.

As will be hereinafter apparent, when the circuit 22 is used inmultiples on a common circuit board, they can be labeled as to theirassociation with specific input and output devices so that the attendantor operator can tell at a glance which input and/or output devices areeither close circuited (input device) or in the AUTO mode and in standby(output device). Alternatively, the attendant can be provided with alocation key from which it is possible to determine the identities ofthe various LED indicators and their associations with the various inputand output devices in the particular system being controlled.

Industrial Application

Referring now to FIG. 2, there is shown a block diagram of a vehiclelaundry 100 comprising a representative combination of input and outputdevices at least some of which are under the control of a smart module160 comprising the microprocessor 8 mounted on a circuit board alongwith a set of seven interface circuits 22A through 22G. The number sevenis arbitrary and chosen to represent the desirability and practicalityof mounting a plurality of interface circuits on a common circuit boardfor local control of a lower hierarchy microprocessor 8 in a systemhaving a higher hierarchy master computer 146. Computer 146 ispreferably capable of managing not only multiple microprocessors 8associated with various components and/or devices of an operatingvehicle laundry but also capable of performing other data processing andretrieval tasks such as financial management, maintenance scheduling,employee attendance and payroll as described generally above.

Referring further to FIG. 2, the vehicle laundry system 100 comprises anelectric motor-driven conveyor 112 which urges vehicles (not shown)along the entire length of a wash/dry lane equipped with a strategicallyarranged sequence of stations equipped with a first class of electricaldevices for sensing conditions pertinent to the operation of the vehiclewasher and dryer system and for producing inputs to the smart modulemicroprocessor representing those conditions. System 100 furthercomprises a second class of devices which are located at the stationsalong the conveyor and which can, when called into action, performvehicle laundering and related functions. Some of these functions areemployed in every wash/dry cycle and others are selectively employedaccording to the wishes and willingness of the customer to pay. Thefirst class of devices include, by way of example, controlling or inputdevices including an electric eye 116 aimed across the vehicle entrypoint to detect the entry of the vehicle into the wash lane and, wheredesired, to accurately measure the length of the vehicle by relating thetime the beam is broken to the speed of operation of the conveyor 112.The input devices further comprise a shaft angle encoder 120 which isintegral with a conveyor sprocket to generate pulses representingincrements of conveyor motion whereby the position of the vehicle as itprogresses through the wash lane can be accurately determined at alltimes.

Devices in the second class which make up the vehicle washer and dryersystem comprise, by way of example, a soap dispenser 122 consisting of afluid reservoir, a pump, a solenoid valve and appropriate plumbing aswill be apparent to those skilled in the art. The controlled devicesfurther comprise vehicle contacting washer brushes 124 which are alsoconventional and may, for example, comprise horizontal or overheadbrushes driven by motors and supported on appropriate movable suspensionsystems as well as vertical or side brushes also equipped with motorsfor rotation purposes and mounted on suitable carriages and/orsuspension systems to operate on the sides of the vehicle and/or to wraparound the vehicle to contact front and rear surfaces as well. Thecontrolled or output devices further comprise a conventional wheelwasher 26 which may be selectively employed to perform special washingoperations on wheels and tires. A sign 128 associated with the wheelwasher 126 is also among the output or controlled devices and consistsof fluorescent or incandescent signage to signal the customer that thewheel washing operation he or she selected as part of the vehicletreatment package is actually operating. The controlled devices furthercomprise a conventional rinse spray 130 also equipped with valves, pumpsand fluid reservoirs as desired to rinse the wash water and soap fromthe surfaces of the vehicle. Rinse spray 130 is followed by anoptionally energized wax applicator station 132 which is anotherconventional output device and associated therewith a fluorescent orincandescent sign 134. Finally, the output devices comprise anarrangement of dryer blowers consisting of electrically operatedturbines, plenum chambers, conduit and appropriate nozzles to remove thewash and rinse water from the exterior surfaces of the vehicle.

The controlling or input devices associated with the laundry system 100further comprise one or more liquid level detectors 138 associated, byway of example, with soap and chemical reservoirs, limit switches 140used to detect or verify vehicle proximity or presence, proximityswitches 42 used to detect or verify the position of various mechanicalcomponents in the system and other devices 144 which may compriseadditional photoelectric eyes, carbon monoxide detectors and emergencystop buttons.

In the system of FIG. 2, all of the components and devices of thevehicle washing and drying system are normally operated and programmedunder the control of a master computer 46 which is preferably located inan attendant station, a convenience store or other facility associatedwith the vehicle laundry 100. The master computer can be any of avariety of commercially available digital processors, usually theso-called "mini computers" and has associated therewith a conventionalinput keyboard 148, hard drive, floppy disk or other associated memory150 and a conventional display screen 152.

The computer 146 has an output connected to a power interface 154 whichconsists of appropriate transformers, circuit breakers,analog-to-digital converters, inverters and rectifiers as necessary tointerface power from conventional sources 56 from power interface 154 toone or more intelligent controller boards 60 hereinafter described indetail. It will be apparent in the following description that numbers inFIG. 2 correspond to reference numbers for identical elements in FIG. 1but that characters A through G have been added in FIG. 2 where multipleelements are used.

The smart module control board 160 comprises an on board microprocessor8 which operates to coordinate the operations of the output devices 122,124, 126, 128, 130, 132, 134 and 136 with the condition signalgenerating input devices 116, 120, 138, 140, 142 and 144 and to ensurethat the laundry 100 operates in accordance with the sequenceestablished by the master control program 146 when it is used toinitialize the microprocessor 8 in establishing the basic program orsequence of operations.

The microprocessor 8 is connected to each of a series of interfacecircuits 22A-22G, the particular number being arbitrary andillustrative; in a practical embodiment, the user may find it convenientto use more or fewer interface circuits per board 160 and a number ofsuch boards per operating system.

Each of the interface circuits 22A-22G is associated with either anindividual controlling (input) device or a controlled (output) device inthe laundry loo to operate either as an input logic level signalinterface or an output logic level signal interface between that deviceand the microprocessor 8. In addition, the interface serves to provideboth local control for manual operation purposes and an annunciatorfunction to visually indicate the operating state of the associateddevice. The manual operation function is provided by way of manualswitches 32A through 32G associated with interfaces 22A through 22G,respectively. The annunciator function is provided by way of three-colorLEDs 86A through 86G associated with respective interface circuits 22Athrough 22G.

By way of example, interface circuit 22A is associated with the shaftangle encoder 120 of the conveyor to function as an input logic levelsignal interface and to provide an input signal to the microprocessor 8indicating the operating state of conveyor; i.e., that the conveyor isor is not propelling one or more vehicles through the system. Interface22B may, by way of example, be associated with the soap dispenser 122and may be locally programmed by way of the microprocessor 8 so that thevalve which opens to permit. soap to be dispensed cannot be operatedunless the microprocessor 8 receives inputs forming a logicalcombination of:

a) high signal indicating that soap reservoir is not empty;

b) high signal indicating that pump motor is on;

c) low signal indicating no emergency stop;

d) high signal indicating that conveyor is operating; and

e) high signal indicating that a vehicle is in the soap area.

If all of these conditions are satisfied, the microprocessor 8 generatesan output signal to the interface circuit 22B turning the soap dispenseron; i.e., opening the soap valve. As described above, a furthercondition to be satisfied is that the three-position switch 32Bassociated with the interface 22B is in the AUTO position and not ineither the "MANUAL" or "OFF" position. Similar logical inputrequirements are established in microprocessor 8 for each of the outputdevices thereby establishing a control logic which is independent of themaster computer 146; i.e., the portion of system 100 wired through board160 is and remains operable even in the event of a failure of the mastercomputer 146.

In conventional fashion, the master computer 146 is also connected toactivate a keypad or token receiver 158, the output of which isconnected to the power interface 154 to power up the vehicle washing anddrying system at the appropriate time after a customer has made apurchase and selected the components of the vehicle treatment he wishesto have applied; e.g., he may wish to omit either or both of the wheelwash or wax applicator. As indicated, the device may be wired around thekeypad or token box to permit direct powering up of the interface 154from the computer 146.

Master computer 146 may be equipped with a variety of operating systemsand application systems including the popular Windows software to assistin establishing appropriate displays in programming one or moremicroprocessor 8. As is well known in the art, the master computer 146and the microprocessor 8 may also function as event monitors; e.g., themicroprocessor 8 may make a record of the activation or energization ofany of the output devices 122, 124, 126, 128, 130, 132, 134 and 136, thetime of day of such operation, the length of such operation, the needfor maintenance, the time and duration of a system failure or breakdown,etc. The master computer 46 may also be provided with additionalprograms to provide management information and management functions suchas maintenance programs, sales record, accounting and personnelemployment and attendance records.

In normal operation, the master computer 46 is operated by way ofkeyboard 148 and the display 152 to activate the token receiver 58 andto activate the power interface 154. The customer places a tokenreceived by him or her from the attendant into the token box 158 as heapproaches the entry of the laundry 100. Alternatively, the customerenters a numerical code via a keypad which may be substituted for thetoken box 158 where desired, thereby to start or enable the start of theoperation of the vehicle wash and dryer system. As the vehicleapproaches the entry, it breaks the beam created by electric eye 116 andenters the conveyor 118. Breaking the beam of electric eye 116 providesan input signal to microprocessor 8 which, along with other logicallycombined signals, commands the appropriate interface circuit 22 to turnON the conveyor motor and activate the shaft angle encoder 120. As thevehicle progresses through the wash lane, urged forward by the conveyor118, the selected combination of output devices 122, 124, 126, 128, 130,132, 134 and 136 is activated or energized in the appropriate sequenceand turned OFF as the vehicle passes that station, all under the controlof the interfaces in the appropriate board 160. This, of course, assumesthat all of the three-position switches 32A through 32G is in the "AUTO"position.

In the event the computer 146 fails, it is possible to continue tooperate the vehicle washer/dryer system to the extent power remainsavailable because the operational programming is provided by localmicroprocessors 8 on boards 160. Moreover, it is possible to energizeundivided devices by manually turning ON the device via the switch 32.Since the logical interrelationship between all of the input and outputdevices and the functions performed thereby is controlled by programmingin the local microprocessors 8, full system operation independent of themaster computer 146 is possible. In addition, it is possible toselectively disable or omit certain of the functions provided by thedevices in the vehicle laundry simply by moving the manualthree-position switches associated therewith on the smart module board160 to the "OFF" position.

By way of summary, the circuit board 60 provides an intelligent moduleby which a plurality of input and output devices can be associated withone another in a predetermined programmed way whereby operation of anoutput device is logically conditioned on a number of input signalconditions associated with one or more input devices or other outputdevices. Because this programmed interrelationship is local to theoperating system; i.e., resident in the memory of the microprocessor 8,it is subject not only to continued operation in the events of thefailure of the master computer 146, but can also be customer tailored toproduce a selected sequence of operations wherein one or more functionsis included or omitted, simply by selectively turning output devices byway of the three-position switch 32. The annunciator LEDs associatedwith the function submodules provide immediate visual indication of theoperating condition of each device; i.e., in the AUTO mode, in theMANUAL mode, or OFF. The annunciator LED also indicates a failed orFAULT condition by going out when the associated device fails for somereason; e.g., an open circuit or short circuit develops. Accordingly,the smart modules 160 perform a number of important functions from locallogical programming to manual operation to fault detection to manualoperation event recording.

While the system of the present invention has been described withreference to use in a vehicle laundry, it is to be understood that theinvention and in particular the circuit boards 160 may be employed toadvantage in any of a variety of multi-function systems wherein alogical interrelationship between the devices causing or producing thefunctions and devices whose operating states act as logical conditionsto the satisfactory performance of system operations are employed. Theapplications software stored in memories 16 and 150 can take many forms.Echelon, by way of example, offers a suitable commercial softwareproduct under the trade name LonWorks. Various examples of suchapplication has been given above.

                  TABLE 1    ______________________________________    R50             33     K ohm    R52             33     K ohm    R55             249    ohm    R57             249    ohm    R59             33     K ohm    R61             249    ohm    R78             8.25   ohm    R76             33     K ohm    R53             475    ohm    C67             1      MF @ 250 V.sub.AC    R96             330    ohm    ______________________________________

We claim:
 1. A relay type interface circuit for an electrical devicecomprising:means defining an energization circuit adapted to beconnected said electrical device and a source of electrical power; saidenergization circuit including a first remotely controllable switch foropening and closing the circuit to the flow of electrical energy;current sensing means connected to the energization circuit forproducing a first output when the energization circuit, including thedevice, is conductive but the first switch is open and a second outputwhen the first switch is closed, a resistivity of said current sensingmeans being substantially greater than a resistivity of the energizationcircuit; and means for remotely controlling the state of the firstswitch.
 2. An interface circuit as described in claim 1 wherein thecurrent sensing means includes an opto-coupler.
 3. A circuit forinterfacing an electrical device having conductive and non-conductiveconditions with a controller of the type which produces commands forcontrolling the condition of an electrical device and which processessignals supplied thereto representing the condition of an electricaldevice comprising:a) a load energization circuit adapted to be connectedbetween the electrical device and a source of electrical power, saidcircuit including a remotely controllable first switch for opening andclosing the circuit and, a second switch for opening and closing thecircuit independently of the first switch; b) current sensing meanscoupled to the power circuit for producing a signal representing theconductive condition of the circuit and the electrical device; c) logiccircuit means for receiving commands from the controller and forgenerating a control signal, the logic circuit means including adifferential amplifier; d) means for coupling said control signal tosaid first switch for controlling the condition of the remotelycontrollable first switch according to the data content of the command;e) the controller being a microprocessor having inputs and outputs, thecurrent sensing means being connected to an input and said logic circuitmeans being connected to an output; and f) an opto-coupler connectedbetween the output of the differential amplifier and said loadenergization circuit and further wherein said first switch is a solidstate switch device having a gate electrode connected to a high voltageside of the opto-coupler.
 4. A circuit for interfacing an electricaldevice having conductive and non-conductive conditions with a controllerof the type which produces commands for controlling the condition of anelectrical device and which processes signals supplied theretorepresenting the condition of an electrical device comprising:a) a loadenergization circuit adapted to be connected between the electricaldevice and a source of electrical power, said circuit including aremotely controllable first switch for opening and closing the circuitand, a second switch for opening and closing the circuit independentlyof the first switch; b) current sensing means coupled to the powercircuit for producing a signal representing the conductive condition ofthe circuit and the electrical device; c) logic circuit means forreceiving commands from the controller and for generating a controlsignal; d) means for coupling said control signal to said first switchfor controlling the condition of the remotely controllable first switchaccording to the data content of the command; e) the controller being amicroprocessor having inputs and outputs, the current sensing meansbeing connected to an input and said logic circuit means being connectedto an output; and said current sensing means including an opto-couplerhaving a high voltage stage connected in parallel with at least aportion of said load energization circuit and a low voltage sideconnected through a differential amplifier to an input of themicroprocessor.
 5. A circuit for interfacing an electrical load devicewith a controller of the type which produces control commands foractivating and deactivating an electrical load device and whichprocesses data signals applied thereto in accordance with a storedprogram comprising:a) a load circuit between the electrical load deviceand a source of electrical power, said circuit including at least afirst remotely controllable switch for opening and closing the circuit;b) current sensing means coupled to said switch for producing an outputsignal when the switch is open but the load device is operative; c)first logic circuit means coupled to said current sensing means forproducing an input signal to the controller in response to the outputsignal; d) second logic circuit means connected to receive commands fromthe controller and for assuming states representing the content of thecommands from the controller received thereby; and the first and secondlogic circuits including differential amplifiers coupled to therespective first and second logic circuits through opto-couplers forisolation from the load circuit; and e) means for rendering the remotelycontrollable switch conductive and non-conductive for controlling theapplication of power to the load device in response to the state of thesecond logic circuit.